“A Liar’s Autobiography” is such a brilliant conceit that you wish, ever so much, that it had come off. An animated resuscitation of Monty Python’s “Dead One,” the late Graham Chapman, this uneven exercise in animated styles and unbalanced riff on his life and work, it’s the closest fans of the now aged Pythons — Terry Jones, Terry Gilliam, John Cleese, Michael Palin, Eric Idle and Carol Cleveland — will get to a genuine reunion of the famed late 60s/early 70s British comedy troupe.

But it feels incomplete, from the bent to the story — Chapman narrates his autobiography for a book on tape a few years before he died of throat cancer in 1989 — to the animation, which seems to have been subcontracted into a lot of hands, only a few of whom were able to match the anarchic feel of Python to the computer-generated imagery they were manipulating.

Chapman was the pipe-smoking ginger at the center of a lot of Python’s most famous sketches, a gay man playing the straight man who might show up in RAF uniform, demand an end to “all the damned silliness,” and prove to be the silliest of all in the process.

He was Arthur in their “Holy Grail” movie, Brian in their Jesus riff, “Life of Brian.” And he was invariably a hoot.

The film lets him tell the story of the day his Mum took him to see policeman Dad during The War, when father was supervising the collecting of body parts after a military plane crash. He recounts childhood vacations, being out of sync with his father (Michael Palin does that voice), an avid reader and future Emmanuel College-Cambridge med student who went to school to join the famed Cambridge “Footlights” comedy group, where he met John Cleese and started down the path to comedy.

He off-handedly tells the story of how the group got its name (getting it sort of wrong, or at least leaving much out), of meeting the other Pythons, of working with the supercilious David Frost, and of discovering his sexuality — that he was, as he slangily put it, on stage and in the book, “a poof.”

That last bit dominates the film. Well, along with his four pints a day alcoholism.

Assorted Python songs are put to use, and the Python tune “Sit on My Face” becomes a vast, overlong animated production number wherein Chapman meets his longtime companion in Ibiza, but spends much of the next 20 years cheating in all manner of drunken male-and-female groupie encounters.

It’s all framed within the best animated bit of all, an extended alcoholic blackout in the middle of a life New York performance of the Oscar Wilde sketch, with Jones, Cleese and Palin waiting for him to remember a lost line. The animation there has cut-outs of the lads’ filmed faces with animated bodies attached.

“There is only one thing in the world worse than being talked about, and that is not being talked about.”

Snippets of an ’80s TV interview in which he talked about his homosexuality and his alcoholism, bits of his work on “The Frost Report,” and a bit of his uproarious funeral are used, in addition to a bizarre but cute animated bit in which Cameron Diaz provides the voice of Sigmund Freud, analyzing the self-loathing/self-absorbed name dropper and his problems.

Conspicuous by his absence, Eric Idle. Also missing, a straight through-line for the autobiography, which jumps about willy nilly, seeking out silly bits and telling bits to illustrate. More’s the pity in this innovative exercise in exhumation, that there aren’t enough of either.